An Internet tool for monitoring, personalized feedback and referral was developed to support routine adolescent preventive care and was compared with usual practice using paper and pencil (P&P). A total of 1071 students (average age 15 years) from seven secondary schools were randomly assigned to the Internet or P&P group. The Internet group received a health and health-behavior assessment, tailored feedback on health and health behavior (specifically fruit consumption), and an online referral to see a physician/nurse if necessary. The P&P group received the same assessment, preprinted generic advice on fruit consumption and a mailed referral (where applicable). Students and physicians/nurses completed evaluation forms to assess indicators of feasibility, acceptability (i.e. satisfaction) and quality of each administration mode. Student participation rate was 87%. The electronic health feedback was positively evaluated. Students perceived the Internet-tailored fruit advice as more pleasant, more personally targeted and more enjoyable, but less credible than the generic preprinted advice (P less than 0.01). No differences in indicators of acceptability and quality of consultation were found (P [greater than or equal to] 0.05). Thus, the Internet can be a valuable tool to support physicians/nurses in the field of preventive care. It is recommended to further optimize and evaluate the Internet as a tool. (Contains 6 tables and 2 figures.)